Divergent boundary

Definition

A divergent boundary is a tectonic plate boundary where two plates move away from each other, leading to the formation of new crust as magma rises to the surface. This process is primarily associated with mid-ocean ridges and rift valleys, where the movement of plates creates spaces for molten rock to erupt and solidify, contributing to the dynamic nature of Earth's surface and its internal processes.

5 Must Know Facts For Your Next Test

1. Divergent boundaries are responsible for the creation of new oceanic crust at mid-ocean ridges, making them a key feature in the process of seafloor spreading.
2. As tectonic plates separate, magma from the mantle rises through fissures to fill the gap, which can result in volcanic activity and the formation of new geological features.
3. The movement at divergent boundaries can also lead to earthquakes, though they tend to be less intense than those at convergent or transform boundaries.
4. The East African Rift is an example of a divergent boundary on land, showcasing how such boundaries can create rift valleys that may eventually lead to the formation of new ocean basins.
5. Divergent boundaries significantly influence magma composition because the upwelling mantle material typically has lower silica content, resulting in basaltic lava flows.

Review Questions

• How do divergent boundaries contribute to the process of seafloor spreading and what geological features do they create?
  • Divergent boundaries play a crucial role in seafloor spreading by allowing tectonic plates to move apart, creating space for magma to rise from the mantle. This results in the formation of mid-ocean ridges where new oceanic crust is generated. As magma cools and solidifies, it forms basaltic rock, contributing to the growth of the ocean floor and creating significant geological features such as underwater mountains.
• Compare and contrast the volcanic activity associated with divergent boundaries and convergent boundaries, focusing on magma composition.
  • Volcanic activity at divergent boundaries typically involves basaltic magma, which has lower silica content and results in relatively gentle eruptions. In contrast, convergent boundaries often produce more explosive volcanic activity due to the subduction of oceanic plates beneath continental plates, leading to more viscous magmas with higher silica content. This difference in magma composition affects not only eruption style but also the types of landforms created by each boundary type.
• Evaluate the long-term geological impact of divergent boundaries on Earth's surface and internal structure over geological time scales.
  • Over geological time scales, divergent boundaries significantly reshape Earth's surface by continuously creating new oceanic crust and modifying existing landforms. As tectonic plates diverge, they lead to the formation of mid-ocean ridges and rift valleys, influencing ocean basin development and continental configurations. This process not only drives plate tectonics but also affects mantle convection patterns and contributes to the dynamic equilibrium of Earth's internal structure, ultimately playing a vital role in our planet's geological evolution.

Related terms

Mid-Ocean Ridge: An underwater mountain range formed by plate tectonics, where new oceanic crust is created as magma rises at divergent boundaries.

Seafloor Spreading: The process by which new oceanic crust is formed at mid-ocean ridges as tectonic plates pull apart, causing magma to rise and solidify.

Rift Valley: A lowland region that forms where tectonic plates are moving apart on land, resulting in a steep-sided valley.